[NVPTX] Prevent fptrunc of v2f32 from being folded into store

Author: AlexMaclean

llvm/lib/Target/NVPTX/NVPTXISelLowering.cpp

@@ -731,6 +731,8 @@ NVPTXTargetLowering::NVPTXTargetLowering(const NVPTXTargetMachine &TM,
   setTruncStoreAction(MVT::f32, MVT::bf16, Expand);
   setTruncStoreAction(MVT::f64, MVT::bf16, Expand);
   setTruncStoreAction(MVT::f64, MVT::f32, Expand);
+  setTruncStoreAction(MVT::v2f32, MVT::v2f16, Expand);
+  setTruncStoreAction(MVT::v2f32, MVT::v2bf16, Expand);
 
   // PTX does not support load / store predicate registers
   setOperationAction(ISD::LOAD, MVT::i1, Custom);

llvm/test/CodeGen/NVPTX/f32x2-instructions.ll

@@ -1960,12 +1960,14 @@ define <2 x float> @test_uitofp_2xi32_to_2xfloat(<2 x i32> %a) #0 {
 define void @test_trunc_to_v2bf16(<2 x float> %a, ptr %p) {
 ; CHECK-LABEL: test_trunc_to_v2bf16(
 ; CHECK:       {
+; CHECK-NEXT:    .reg .b32 %r<4>;
 ; CHECK-NEXT:    .reg .b64 %rd<3>;
 ; CHECK-EMPTY:
 ; CHECK-NEXT:  // %bb.0:
 ; CHECK-NEXT:    ld.param.b64 %rd2, [test_trunc_to_v2bf16_param_1];
-; CHECK-NEXT:    ld.param.b64 %rd1, [test_trunc_to_v2bf16_param_0];
-; CHECK-NEXT:    st.b32 [%rd2], %rd1;
+; CHECK-NEXT:    ld.param.v2.b32 {%r1, %r2}, [test_trunc_to_v2bf16_param_0];
+; CHECK-NEXT:    cvt.rn.bf16x2.f32 %r3, %r2, %r1;
+; CHECK-NEXT:    st.b32 [%rd2], %r3;
 ; CHECK-NEXT:    ret;
   %trunc = fptrunc <2 x float> %a to <2 x bfloat>
   store <2 x bfloat> %trunc, ptr %p
@@ -1975,12 +1977,14 @@ define void @test_trunc_to_v2bf16(<2 x float> %a, ptr %p) {
 define void @test_trunc_to_v2f16(<2 x float> %a, ptr %p) {
 ; CHECK-LABEL: test_trunc_to_v2f16(
 ; CHECK:       {
+; CHECK-NEXT:    .reg .b32 %r<4>;
 ; CHECK-NEXT:    .reg .b64 %rd<3>;
 ; CHECK-EMPTY:
 ; CHECK-NEXT:  // %bb.0:
 ; CHECK-NEXT:    ld.param.b64 %rd2, [test_trunc_to_v2f16_param_1];
-; CHECK-NEXT:    ld.param.b64 %rd1, [test_trunc_to_v2f16_param_0];
-; CHECK-NEXT:    st.b32 [%rd2], %rd1;
+; CHECK-NEXT:    ld.param.v2.b32 {%r1, %r2}, [test_trunc_to_v2f16_param_0];
+; CHECK-NEXT:    cvt.rn.f16x2.f32 %r3, %r2, %r1;
+; CHECK-NEXT:    st.b32 [%rd2], %r3;
 ; CHECK-NEXT:    ret;
   %trunc = fptrunc <2 x float> %a to <2 x half>
   store <2 x half> %trunc, ptr %p